Comparison of nifedipine GITS and hydrochlorothiazide in the management of elderly patients with stage I-III diastolic hypertension.

Abstract

A randomized, double blind, parallel study was performed to compare the effects of nifedipine gastrointestinal therapeutic system (GITS) to hydrochlorothiazide (HCTZ) in the management of the elderly hypertensive. Eighteen patients, mean age 65 +/- 5 years, with Stage I-III diastolic hypertension (sitting diastolic BP between 90 and 115 mm HG) were included in each treatment group. Following a 2 to 8 week placebo washout phase, patients received either nifedipine GITS or HCTZ and were titrated over 5 weeks to achieve a goal diastolic blood pressure less than 90 mm Hg. Patients were then continued on medication during an 8 week maintenance phase. Treatment effect on systolic and diastolic blood pressure was assessed. Serum electrolytes, lipids, blood urea nitrogen, and creatinine were measured before and after treatment. Posttreatment changes in renal and cardiovascular function, as well as left ventricular mass were evaluated. The results showed significant reductions in systolic and diastolic blood pressure with both drugs; no treatment difference was found, although goal blood pressure was achieved more rapidly with nifedipine GITS (28 v 34 days, P < .05). BUN was significantly increased only after diuretic therapy (P < .01) and serum potassium fell to a greater degree with HCTZ (0.3 mEq/L v 0.1 mEq/L) than with nifedipine GITS. No statistically significant changes in left ventricular mass, ejection fraction, glomerular filtration rate, or renal blood flow were seen after therapy with either drug. However, the time peak LV diastolic filling rate decreased with nifedipine GITS (197 to 164 msec) and increased with HCTZ (172 to 198 msec). This treatment difference approached statistical significance (P = .07). Adverse side effects of treatment were reported by 50% of nifedipine GITS patients and 28% of patients treated with HCTZ. This treatment difference was not statistically significant. We conclude that both nifedipine GITS and HCTZ monotherapy provide significant blood pressure reduction in older hypertensives with Stage I-III diastolic hypertension. Both drugs are well tolerated with no significant adverse effect on renal or cardiovascular function after short term therapy.